A computerized network contains more than one node and more than one link between the nodes. In large scale networks involving large amounts of nodes and links and transporting a large amount of traffic, IP network design and transport network design is crucial. Efficient network designs reduce network traffic problems, try to ensure that all nodes can access and send traffic efficiently, and may ensure that the failure of one node or link does not endanger the rest of the nodes and links from functioning effectively. Efficient network designs also minimize the overall cost of the network, by effectively utilizing links and positioning core routers in a way to minimize the total number of core routers.
IP network design and transport network design are typically completed as separate tasks. Implementing and optimizing one first and then the other may not optimize the overall network, resulting in an overall sub-optimal network design.